BVH-A2 and BVH-A3 antigens of group B Streptococcus

ABSTRACT

Group B  streptococcus  polypeptides and polynucleotides encoding them are disclosed. Said polypeptides may be useful for the prophylaxis, diagnostic and/or therapy of streptococcal infection in mammals. Also disclosed are recombinant methods of producing the polypeptide antigens as well as diagnostic assays for detecting streptococcal infections, particularly GBS.

This application claims the benefit of U.S. provisional application Ser. No. 60/239,919, filed Oct. 13, 2000.

FIELD OF THE INVENTION

The present invention is related to polypeptides of Group B Streptococcus (GBS) (S. agalactiae) and corresponding DNA fragments, which may be useful to prevent, diagnose and/or treat GBS infections in individuals such as humans.

BACKGROUND OF THE INVENTION

Streptococcus are gram (+) bacteria that are differentiated by group specific carbohydrate antigens A through O found on their cell surface. Streptococcus groups are further distinguished by type-specific capsular polysaccharide antigens. Several serotypes have been identified for the GBS: Ia, Ib, II, III, IV, V, VI, VII and VIII. GBS also contains antigenic proteins known as “C-proteins” (alpha, beta, gamma and delta), some of which have been cloned.

Although GBS is a common component of the normal human vaginal and colonic flora this pathogen has long been recognized as a major cause of infections in neonates, expectant mothers, some non-pregnant adults as well as mastitis in dairy herds. Expectant mothers exposed to GBS are at risk of postpartum infection and may transfer the infection to their baby as the child passes through the birth canal.

GBS infections in infants are restricted to very early infancy. Approximately 80% of infant infections occur in the first days of life, so-called early-onset disease. Late-onset infections occur in infants between 1 week and 2 to 3 months of age. Clinical syndromes of GBS disease in newborns include sepsis, meningitis, pneumonia, cellulitis, osteomyelitis, septic arthritis, endocarditis, epiglottis. In addition to acute illness due to GBS, which is itself costly, GBS infections in newborns can result in death, disability, and, in rare instances, recurrence of infection. Although the organism is sensitive to antibiotics, the high attack rate and rapid onset of sepsis in neonates and meningitis in infants results in high morbidity and mortality.

Among pregnant women, GBS causes clinical illness ranging from mild urinary tract infection to life-threatening sepsis and meningitis, including also osteomyelitis, endocarditis, amniotis, endometritis, wound infections (postcesarean and postepisiotomy), cellulitis, fasciitis.

Among non-pregnant adults, the clinical presentations of invasive GBS disease most often take the form of primary bacteremia but also skin of soft tissue infection, pneumonia, urosepsis, endocarditis, peritonitis, meningitis, empyema. Skin of soft tissue infections include cellulitis, infected peripheral ulcers, osteomyelitis, septic arthritis and decubiti or wound infections. Among people at risk, there are debilitated hosts such as people with a chronic disease such as diabetes mellitus and cancer, or elderly people.

GBS infections can also occur in animals and cause mastitis in dairy herds.

To find a vaccine that will protect hosts from GBS infection, researches have turned to the type-specific antigens. Unfortunately these polysaccharides have proven to be poorly immunogenic in hosts and are restricted to the particular serotype from which the polysaccharide originates. Further, capsular polysaccharide elicit a T cell independent response i.e. no IgG production. Consequently capsular polysaccharide antigens are unsuitable as a vaccine component for protection against GBS infection.

Others have focused on the C-protein beta antigen which demonstrated immunogenic properties in mice and rabbit models. This protein was found to be unsuitable as a human vaccine because of its undesirable property of interacting with high affinity and in a non-immunogenic manner with the Fc region of human IgA. The C-protein alpha antigen is rare in type III serotypes of GBS which is the serotype responsible for most GBS mediated conditions and is therefore of little use as a vaccine component.

There remains an unmet need for GBS polypeptides that may be useful to prevent, diagnose and/or treat GBS infections in individuals such as humans.

SUMMARY OF THE INVENTION

According to one aspect, the present invention provides an isolated polynucleotide encoding a polypeptide having at least 70% identity to a second polypeptide comprising a sequence chosen from SEQ ID NOS: 3, 4, 7 and 8 or fragments or analogs thereof.

According to one aspect, the present invention relates to polypeptides which comprise an amino acid sequence selected from SEQ ID NOS: 3, 4, 7 and 8 or fragments or analogs thereof.

In other aspects, there are provided polypeptides encoded by polynucleotides of the invention, pharmaceutical compositions, vectors comprising polynucleotides of the invention operably linked to an expression control region, as well as host cells transfected with said vectors and processes of producing polypeptides comprising culturing said host cells under conditions suitable for expression.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 represents the DNA sequence of BVH-A2 gene from serotype III Group B streptococcus strain NCS954; SEQ ID NO: 1.

FIG. 2 represents the DNA sequence of BVH-A2 gene from serotype III Group B streptococcus strain NCS954 without the region coding for its leader peptide; SEQ ID NO: 2.

FIG. 3 represents the amino acid sequence of BVH-A2polypeptide from serotype III Group B streptococcus strain NCS954; SEQ ID NO: 3.

FIG. 4 represents the amino acid sequence of BVH-A2 polypeptide from serotype III Group B streptococcus strain NCS954 without the 37 amino acid residues leader peptide; SEQ ID NO: 4.

FIG. 5 represents the DNA sequence of BVH-A3 gene from serotype III Group B streptococcus strain NCS954; SEQ ID NO: 5.

FIG. 6 represents the DNA sequence of BVH-A3 gene from serotype III Group B streptococcus strain NCS954 without the region coding for the leader peptide; SEQ ID NO: 6.

FIG. 7 represents the amino acid sequence of BVH-A3 polypeptide from serotype III Group B streptococcus strain NCS954; SEQ ID NO: 7.

FIG. 8 represents the amino acid sequence of BVH-A3 polypeptide from serotype III Group B streptococcus strain NCS954 without the 2 amino acid residues leader peptide; SEQ ID NO: 8.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides purified and isolated polynucleotides, which encode Group B Streptococcal polypeptides that may be used to prevent, treat, and/or diagnose streptococcal infection. The present invention provides four separate preferred polynucleotides, each individually and separately defined by one of SEQ ID NOS 1, 2, 5 and 6. Further provided in the present invention are four separate polypeptides, each individually and separately defined by one of seq ID NOS: 3, 4, 7 and 8. Those skilled in the art will appreciate that the invention includes polynucleotides that encode analogs such as mutants, variants, homologues and derivatives of such polypeptides, as described herein in the present patent application. The invention also includes RNA molecules corresponding to the DNA molecules of the invention. In addition to the DNA and RNA molecules, the invention includes the corresponding polypeptides and monospecific antibodies that specifically bind to such polypeptides.

According to one aspect, the present invention provides an isolated polynucleotide encoding a polypeptide having at least 70% identity to a second polypeptide comprising a sequence chosen from SEQ ID NOS: 3, 4, 7 and 8 or fragments or analogs thereof.

According to one aspect, the present invention provides an isolated polynucleotide encoding a polypeptide having at least 80% identity to a second polypeptide comprising a sequence chosen from SEQ ID NOS: 3, 4, 7 and 8 or fragments or analogs thereof.

According to one aspect, the present invention provides an isolated polynucleotide encoding a polypeptide having at least 85% identity to a second polypeptide comprising a sequence chosen from SEQ ID NOS: 3, 4, 7 and 8 or fragments or analogs thereof.

According to one aspect, the present invention provides an isolated polynucleotide encoding a polypeptide having at least 90% identity to a second polypeptide comprising a sequence chosen from SEQ ID NOS: 3, 4, 7 and 8 or fragments or analogs thereof.

According to one aspect, the present invention provides an isolated polynucleotide encoding a polypeptide having at least 95% identity to a second polypeptide comprising a sequence chosen from SEQ ID NOS: 3, 4, 7 and 8 or fragments or analogs thereof.

According to one aspect, the present invention provides an isolated polynucleotide encoding a polypeptide comprising a sequence chosen from SEQ ID NOS: 3, 4, 7 and 8 or fragments or analogs thereof.

According to one aspect, the present invention relates to polynucleotides encoding an epitope bearing portion of a polypeptide having a sequence chosen from SEQ ID NOS: 3, 4, 7 and 8 or fragments or analogs thereof.

According to one aspect, the present invention relates to epitope bearing portions of a polypeptide having a sequence chosen from SEQ ID NOS: 3, 4, 7 and 8 or fragments or analogs thereof.

According to one aspect, the present invention relates to polypeptides comprising an amino acid sequence comprising sequences from SEQ ID NOS: 3, 4, 7 and 8 or fragments or analogs thereof.

According to one aspect, the present invention provides an isolated polynucleotide encoding a polypeptide having at least 70% identity to a second polypeptide comprising a sequence chosen from SEQ ID NOS: 3, 4, 7 and 8.

According to one aspect, the present invention provides an isolated polynucleotide encoding a polypeptide having at least 80% identity to a second polypeptide comprising a sequence chosen from SEQ ID NOS: 3, 4, 7 and 8.

According to one aspect, the present invention provides an isolated polynucleotide encoding a polypeptide having at least 85% identity to a second polypeptide comprising a sequence chosen from SEQ ID NOS: 3, 4, 7 and 8.

According to one aspect, the present invention provides an isolated polynucleotide encoding a polypeptide having at least 90% identity to a second polypeptide comprising a sequence chosen from SEQ ID NOS: 3, 4, 7 and 8.

According to one aspect, the present invention provides an isolated polynucleotide encoding a polypeptide having at least 95% identity to a second polypeptide comprising a sequence chosen from SEQ ID NOS: 3, 4, 7 and 8.

According to one aspect, the present invention provides an isolated polynucleotide encoding a polypeptide comprising a sequence chosen from SEQ ID NOS: 3, 4, 7 and 8.

According to one aspect, the present invention relates to polynucleotides encoding an epitope bearing portion of a polypeptide having a sequence chosen from SEQ ID NOS: 3, 4, 7 and 8.

According to one aspect, the present invention relates to epitope bearing portions of a polypeptide having a sequence chosen from SEQ ID NOS: 3, 4, 7 and 8.

In a further embodiment, the present invention also relates to polynucleotides encoding a polypeptide which is able to raise antibodies having binding specificity for a polypeptide having a sequence chosen from SEQ ID NOS: 3, 4, 7 and 8 or fragments or analogs thereof.

In a further embodiment, the present invention also relates to polynucleotides encoding a polypeptide which is able to raise antibodies having binding specificity for a polypeptide having a sequence chosen from SEQ ID NOS: 3, 4, 7 and 8.

The percentage of homology is defined as the sum of the percentage of identity plus the percentage of similarity or conservation of amino acid type.

One can use a program such as the CLUSTAL program to compare amino acid sequences. This program compares amino acid sequences and finds the optimal alignment by inserting spaces in either sequence as appropriate. It is possible to calculate amino acid identity or similarity (identity plus conservation of amino acid type) for an optimal alignment. A program like BLASTx will align the longest stretch of similar sequences and assign a value to the fit. It is thus possible to obtain a comparison where several regions of similarity are found, each having a different score. Both types of identity analysis are contemplated in the present invention.

In a further embodiment, the polypeptides in accordance with the present invention are antigenic.

In a further embodiment, the polypeptides in accordance with the present invention are immunogenic.

In a further embodiment, the polypeptides in accordance with the present invention can elicit an immune response in a individual.

In a further embodiment, the present invention also relates to polypeptides which are able to raise antibodies having binding specificity to the polypeptides of the present invention as defined above.

In a further embodiment, the present invention also relates to polypeptides which are able to raise antibodies having binding specificity for a polypeptide having a sequence chosen from SEQ ID NOS: 3, 4, 7 and 8 or fragments or analogs thereof.

In a further embodiment, the present invention also relates to polypeptides which are able to raise antibodies having binding specificity for a polypeptide having a sequence chosen from SEQ ID NOS: 3, 4, 7 and 8.

An antibody that “has binding specificity” is an antibody that recognises and binds the selected polypeptide but which does not substantially recognise and bind other molecules in a sample, e.g., a biological sample which naturally includes the selected peptide. Specific binding can be measured using an ELISA assay in which the selected polypeptide is used as an antigen.

In accordance with the present invention, “protection” in the biological studies is defined by a significant increase in the survival curve, rate or period. Statistical analysis using the Log rank test to compare survival curves, and Fisher exact test to compare survival rates and numbers of days to death, respectively, might be useful to calculate P values and determine whether the difference between the two groups is statistically significant. P values of 0.05 are regarded as not significant.

In an additional aspect of the invention there are provided antigenic/immunogenic fragments of the polypeptides of the invention, or of analogs thereof.

The fragments of the present invention should include one or more such epitopic regions or be sufficiently similar to such regions to retain their antigenic/immunogenic properties. Thus, for fragments according to the present invention the degree of identity is perhaps irrelevant, since they may be 100% identical to a particular part of a polypeptide or analog thereof as described herein. The present invention further provides fragments having at least 10 contiguous amino acid residues from the polypeptide sequences of the present invention. In one embodiment, at least 15 contiguous amino acid residues. In one embodiment, at least 20 contiguous amino acid residues.

The skilled person will appreciate that “fragments”, “analogs” or “derivatives” of the polypeptides of the invention will also find use in the context of the present invention, i.e. as antigenic/immunogenic material. Thus, for instance polypeptides which include one or more additions, deletions, substitutions or the like are encompassed by the present invention.

As used herein, “analogs” of the polypeptides of the invention include those polypeptides in which one or more of the amino acid residues are substituted with a conserved amino acid residue (preferably conserved) and which may be natural or unnatural. In one embodiment, analogs of polypeptides of the invention will have about 70% identity with those sequences illustrated in the figures or fragments thereof. That is, 70% of the residues are the same. In a further embodiment, polypeptides will have greater than 80% identity. In a further embodiment, polypeptides will have greater than 90% identity. In a further embodiment, polypeptides will have greater than 95% identity. In a further embodiment, polypeptides will have greater than 99% identity. In a further embodiment, analogs of polypeptides of the invention will have fewer than about 20 amino acid residue substitutions, modifications or deletions and more preferably less than 10.

In one embodiment, derivatives and analogs of polypeptides of the invention will have about 70% homology with those sequences illustrated in the figures or fragments thereof. In a further embodiment, derivatives and analogs of polypeptides will have greater than 80% homology. In a further embodiment, derivatives and analogs of polypeptides will have greater than 90% homology. In a further embodiment, derivatives and analogs of polypeptides will have greater than 95% homology. In a further embodiment, derivatives and analogs of polypeptides will have greater than 99% homology. In a further embodiment, derivatives and analogs of derivatives and analogs of polypeptides of the invention will have fewer than about 20 amino acid residue substitutions, modifications or deletions and more preferably less than 10.

According to a further aspect, the invention provides polypeptides having at least 70% identity to a second polypeptide having an amino acid sequence chosen from: SEQ ID NOS: 3, 4, 7 and 8 or fragments or analogs thereof.

According to a further aspect, the invention provides polypeptides having at least 80% identity to a second polypeptide having an amino acid sequence chosen from: SEQ ID NOS: 3, 4, 7 and 8 or fragments or analogs thereof.

According to a further aspect, the invention provides polypeptides having at least 85% identity to a second polypeptide having an amino acid sequence chosen from: SEQ ID NOS: 3, 4, 7 and 8 or fragments or analogs thereof.

According to a further aspect, the invention provides polypeptides having at least 90% identity to a second polypeptide having an amino acid sequence chosen from: SEQ ID NOS: 3, 4, 7 and 8 or fragments or analogs thereof.

According to a further aspect, the invention provides polypeptides having at least 95% identity to a second polypeptide having an amino acid sequence chosen from: SEQ ID NOS: 3, 4, 7 and 8 or fragments or analogs thereof.

According to a further aspect, the invention provides polypeptides comprising a sequence chosen from: SEQ ID NOS: 3, 4, 7 and 8 or fragments or analogs thereof.

According to a further aspect, the invention provides polypeptides characterized by a sequence chosen from: SEQ ID NOS: 3, 4, 7 and 8 or fragments or analogs thereof.

According to a further aspect, the invention provides polypeptides having at least 70% identity to a second polypeptide having an amino acid sequence chosen from: SEQ ID NOs: 3, 4, 7 and 8.

According to a further aspect, the invention provides polypeptides having at least 80% identity to a second polypeptide having an amino acid sequence chosen from: SEQ ID NOS: 3, 4, 7 and 8.

According to a further aspect, the invention provides polypeptides having at least 85% identity to a second polypeptide having an amino acid sequence chosen from: SEQ ID NOS: 3, 4, 7 and 8.

According to a further aspect, the invention provides polypeptides having at least 90% identity to a second polypeptide having an amino acid sequence chosen from: SEQ ID NOS: 3, 4, 7 and 8.

According to a further aspect, the invention provides polypeptides having at least 95% identity to a second polypeptide having an amino acid sequence chosen from: SEQ ID NOS: 3, 4, 7 and 8.

According to a further aspect, the invention provides polypeptides comprising a sequence chosen from: SEQ ID NOS: 3, 4, 7 and 8.

According to a further aspect, the invention provides polypeptides characterized by a sequence chosen from: SEQ ID NOS: 3, 4, 7 and 8.

These substitutions are those having a minimal influence on the secondary structure and hydropathic nature of the polypeptide. Preferred substitutions are those known in the art as conserved, i.e. the substituted residues share physical or chemical properties such as hydrophobicity, size, charge or functional groups. These include substitutions such as those described by Dayhoff, M. in Atlas of Protein Sequence and Structure 5, 1978 and by Argos, P. in EMBO J. 8, 779-785, 1989. For example, amino acids, either natural or unnatural, belonging to one of the following groups represent conservative changes:

-   ala, pro, gly, gln, asn, ser, thr, val; -   cys, ser, tyr, thr; -   val, ile, leu, met, ala, phe; -   lys, arg, orn, his; -   and phe, tyr, trp, his.

The preferred substitutions also include substitutions of D-enantiomers for the corresponding L-amino acids.

Preferably, a fragment, analog or derivative of a polypeptide of the invention will comprise at least one antigenic region i.e. at least one epitope.

In an alternative approach, the analogs could be fusion polypeptides, incorporating moieties which render purification easier, for example by effectively tagging the desired polypeptide. It may be necessary to remove the “tag” or it may be the case that the fusion polypeptide itself retains sufficient antigenicity to be useful.

Thus, what is important for analogs, derivatives and fragments is that they possess at least a degree of the antigenicity/immunogenicity of the polypeptides of the invention from which they are derived.

Also included are polypeptides which have fused thereto other compounds which alter the biological or pharmacological properties of the polypeptide, i.e., polyethylene glycol (PEG) to increase half-life, leader or secretory amino acid sequences for ease of purification, prepro- and pro-sequences and (poly)saccharides.

Furthermore, in those situations where amino acid regions are found to be polymorphic, it may be desirable to vary one or more particular amino acids to more effectively mimic the different epitopes of the different GBS strains.

Moreover, the polypeptides of the present invention can be modified by terminal —NH₂ acylation (e.g. by acetylation or thioglycolic acid amidation, terminal carboxy amidation, e.g. with ammonia or methylamine) to provide stability, increased hydrophobicity for linking or binding to a support or other molecule.

Also contemplated are hetero and homo polypeptide multimers of the polypeptide fragments and analogues. These polymeric forms include, for example, one or more polypeptides that have been cross-linked with cross-linkers such as avidin/biotin, glutaraldehyde or dimethylsuperimidate. Such polymeric forms also include polypeptides containing two or more tandem or inverted contiguous sequences, produced from multicistronic mRNAs generated by recombinant DNA technology.

In a further embodiment, the present invention also relates to chimeric polypeptides which comprise one or more polypeptides or fragments or analogs or derivatives thereof as defined in the figures of the present application.

In a further embodiment, the present invention also relates to chimeric polypeptides comprising two or more polypeptides having a sequence chosen from SEQ ID NOS: 3, 4, 7 and 8 or fragments or analogs thereof; provided that the polypeptides are linked as to formed a chimeric polypeptide.

In a further embodiment, the present invention also relates to chimeric polypeptides comprising two or more polypeptides having a sequence chosen from SEQ ID NOS: 3, 4, 7 and 8 provided that the polypeptides are linked as to formed a chimeric polypeptide.

In order to achieve the formation of antigenic polymers (i.e. synthetic multimers), polypeptides may be utilized having bishaloacetyl groups, nitroarylhalides, or the like, where the reagents being specific for thio groups. Therefore, the link between two mercapto groups of the different peptides may be a single bound or may be composed of a linking group of at least two, typically at least four and not more than 16, but usually not more than about 14 carbon atoms.

In a particular embodiment, polypeptide fragments or analogs of the invention do not contain a methionine (Met) starting residue. Preferably, polypeptides will not incorporate a leader or secretory sequence (signal sequence). The signal portion of a polypeptide of the invention may be determined according to established molecular biological techniques. In general,the polypeptide of interest may be isolated from GBS culture and subsequently sequenced to determine the initial residue of the mature protein and therefore the sequence of the mature polypeptide.

According to another aspect of the invention, there are also provided (i) a composition of matter containing a polypeptide of the invention, together with a carrier, diluent or adjuvant; (ii) a pharmaceutical composition comprising a polypeptide of the invention and a carrier, diluent or adjuvant; (iii) a vaccine comprising a polypeptide of the invention and a carrier, diluent or adjuvant; (iv) a method for inducing an immune response against GBS, in an individual, by administering to the individual, an immunogenically effective amount of a polypeptide of the invention to elicit an immune response, e.g., a protective immune response to GBS; and particularly, (v) a method for preventing and/or treating a GBS infection, by administering a prophylactic or therapeutic amount of a polypeptide of the invention to an individual in need.

Before immunization, the polypeptides of the invention can also be coupled or conjugated to carrier proteins such as tetanus toxin, diphtheria toxin, hepatitis B virus surface antigen, poliomyelitis virus VP1 antigen or any other viral or bacterial toxin or antigen or any suitable proteins to stimulate the development of a stronger immune response. This coupling or conjugation can be done chemically or genetically. A more detailed description of peptide-carrier conjugation is available in Van Regenmortel, M. H. V., Briand J. P., Muller S., Plaué S., <<Synthetic Polypeptides as antigens>> in Laboratory Techniques in Biochemistry and Molecular Biology, Vol.19 (ed.) Burdou, R. H. & Van Knippenberg P. H. (1988), Elsevier New York.

According to another aspect, there are provided pharmaceutical compositions comprising one or more GBS polypeptides of the invention in a mixture with a pharmaceutically acceptable carrier diluent or adjuvant. Suitable adjuvants include (1) oil-in-water emulsion formulations such as MF59™, SAF™, Ribi™; (2) Freund's complete or incomplete adjuvant; (3) salts i.e. AlK(SO₄)₂, AlNa(SO₄)₂, AlNH₄(SO₄)₂, Al(OH)₃, AlPO₄, silica, kaolin; (4) saponin derivatives such as Stimulon™ or particles generated therefrom such as ISCOMs (immunostimulating complexes); (5) cytokines such as interleukins, interferons, macrophage colony stimulating factor (M-CSF), tumor necrosis factor (TNF); (6) other substances such as carbon polynucleotides i.e. poly IC and poly AU, detoxified cholera toxin (CTB) and E.coli heat labile toxin for induction of mucosal immunity. A more detailed description of adjuvant is available in a review by M. Z. I Khan et al. in Pharmaceutical Research, vol. 11, No. 1 (1994) pp 2-11, and also in another review by Gupta et al., in Vaccine, Vol. 13, No. 14, pp 1263-1276 (1995) and in WO 99/24578. Preferred adjuvants include QuilA™, QS21™, Alhydrogel™ and Adjuphos™.

Pharmaceutical compositions of the invention may be administered parenterally by injection, rapid infusion, nasopharyngeal absorption, dermoabsorption, or buccal or oral.

Pharmaceutical compositions of the invention are used for the treatment or prophylaxis of streptococcal infection and/or diseases and symptoms mediated by streptococcal infection, in particular Group A streptococcus (S.pyogenes), Group B streptococcus (GBS or S.agalactiae), S.dysgalactiae, S.uberis, S.nocardia as well as Staphylococcus aureus. General information about Streptococcus, and more particularly GBS, is available in Manual of Clinical Microbiology by P. R. Murray et al. (1995, 6^(th) Edition, ASM Press, Washington, D.C.).

In one embodiment, pharmaceutical compositions of the invention are used for the treatment or prophylaxis of GBS infection and/or diseases and symptoms mediated by GBS infection.

In a particular embodiment, pharmaceutical compositions of the invention are administered to those individuals at risk of GBS infection such as pregnant women for mild urinary tract infection to life-threatening sepsis and meningitis, including also osteomyelitis, endocarditis, amniotis, endometritis, wound infections (postcesarean and postepisiotomy), cellulitis, fasciitis.

In a particular embodiment, pharmaceutical compositions of the invention are administered to those individuals at risk of GBS infection such as neonates and infants for sepsis, meningitis, pneumonia, cellulitis, osteomyelitis, septic arthritis, endocarditis, epiglottis.

In a particular embodiment, pharmaceutical compositions of the invention are administered to those individuals at risk of GBS infection such as non-pregnant adults, for primary bacteremia but also skin of soft tissue infection, pneumonia, urosepsis, endocarditis, peritonitis, meningitis, empyema. Skin of soft tissue infections include cellulitis, infected peripheral ulcers, osteomyelitis, septic arthritis and decubiti or wound infections. Among people at risk, there are debilitated individuals such as people with a chronic disease such as diabetes mellitus and cancer, or elderly people.

In a particular embodiment, pharmaceutical compositions of the invention are administered to those individuals at risk of GBS infection such as cattle for the treatment of mastitis in cattle.

In a further aspect, the invention provides the use of pharmaceutical composition of the invention for the prophylactic or therapeutic treatment of GBS bacterial infection in an individual susceptible to GBS infection comprising administering to said individual a therapeutic or prophylactic amount of a composition of the invention.

According to a further aspect, the GBS polypeptides of the invention may be used in a kit comprising the polypeptides of the invention for detection of diagnosis of GBS infection.

As used in the present application, the term “individual” include mammals. In a further embodiment, the mammals are humans. In a further embodiment, the mammals are non-humans, such as herds.

In a particular embodiment, pharmaceutical compositions of the invention are administered to those individuals at risk of GBS infection such as neonates.

Pharmaceutical compositions of the invention are preferably in unit dosage form of about 0.001 to 100 μg/kg (antigen/body weight) and more preferably 0.01 to 10 μg/kg and most preferably 0.1 to 1 μg/kg, 1 to 3 times with an interval of about 1 to 6 week intervals between immunisations.

Pharmaceutical compositions are preferably in unit dosage form of about 0.1 μg to 10 mg and more preferably 1 μg to 1 mg and most preferably 10 to 100 μg 1 to 3 times with an interval of about 1 to 6 week intervals between immunizations.

In one embodiment, polynucleotides are those illustrated in SEQ ID NOS: 1, 2, 5 and 6 which may include the open reading frames (ORF), encoding the polypeptides of the invention.

In one embodiment, polynucleotides are those illustrated in SEQ ID NOS: 1, 2, 5 and 6 encoding the polypeptides of the invention.

It will be appreciated that the polynucleotide sequences illustrated in the figures may be altered with degenerated codons yet still encode the polypeptides of the invention. Accordingly the present invention further provides polynucleotides herein above described (or the complement sequence thereof) having 50% identity between sequences. In one embodiment, at least 70% identity between sequences. In one embodiment, at least 75% identity between sequences. In one embodiment, at least 80% identity between sequences. In one embodiment, at least 85% identity between sequences. In one embodiment, at least 90% identity between sequences. In a further embodiment, polynucleotides are hybridizable under stringent conditions, i.e. having at least 95% identity. In a further embodiment, more than 97% identity.

Suitable stringent conditions for hybridation can be readily determined by one of skilled in the art (see for example Sambrook et al., (1989) Molecular cloning: A Laboratory Manual, 2^(nd) ed, Cold Spring Harbor, N.Y.; Current Protocols in Molecular Biology, (1999) Edited by Ausubel F. M. et al., John Wiley & Sons, Inc., N.Y.).

In a further embodiment, the present invention provides polynucleotides that hybridize under stringent conditions to either

-   (a) a polynucleotide encoding a polypeptide or -   (b) the complement of a polynucleotide encoding a polypeptide;     wherein said polypeptide comprises SEQ ID NO: 3, 4, 7 and 8, or     fragments or analogs thereof.

In a further embodiment, the present invention provides polynucleotides that hybridize under stringent conditions to either

-   (a) a polynucleotide encoding a polypeptide or -   (b) the complement of a polynucleotide encoding a polypeptide;     wherein said polypeptide comprises at least 10 contiguous amino acid     residues from a polypeptide comprising SEQ ID NO: 3, 4, 7 and 8 or     fragments or analogs thereof.

In a further embodiment, the present invention provides polynucleotides that hybridize under stringent conditions to either

-   (a) a polynucleotide encoding a polypeptide or -   (b) the complement of a polynucleotide encoding a polypeptide;     wherein said polypeptide comprises SEQ ID NO: 3, 4, 7 and 8.

In a further embodiment, the present invention provides polynucleotides that hybridize under stringent conditions to either

-   (a) a polynucleotide encoding a polypeptide or -   (b) the complement of a polynucleotide encoding a polypeptide;     wherein said polypeptide comprises at least 10 contiguous amino acid     residues from a polypeptide comprising SEQ ID NO: 3, 4, 7 and 8.

As will be readily appreciated by one skilled in the art, polynucleotides include both DNA and RNA.

The present invention also includes polynucleotides complementary to the polynucleotides described in the present application.

In a further aspect, polynucleotides encoding polypeptides of the invention, or fragments or analogs thereof, may be used in a DNA immunization method. That is, they can be incorporated into a vector which is replicable and expressible upon injection thereby producing the antigenic polypeptide in vivo. For example polynucleotides may be incorporated into a plasmid vector under the control of the CMV promoter which is functional in eukaryotic cells. Preferably, the vector is injected intramuscularly.

According to another aspect, there is provided a process or method of manufacturing for producing polypeptides of the invention by recombinant techniques by expressing a polynucleotide encoding said polypeptide in a host cell and recovering the expressed polypeptide product. Alternatively, the polypeptides can be produced according to established synthetic chemical techniques, i.e. solution phase or solid phase synthesis of oligopeptides which are ligated to produce the full polypeptide (block ligation).

General methods for obtention and evaluation of polynucleotides and polypeptides are described in the following references: Sambrook et al., (1989) Molecular cloning: A Laboratory Manual, 2^(nd) ed, Cold Spring Harbor, N.Y.; Current Protocols in Molecular Biology, (1999) Edited by Ausubel F. M. et al., John Wiley & Sons, Inc., N.Y.; PCR Cloning Protocols, from Molecular Cloning to Genetic Engineering, (1997) Edited by White B. A., Humana Press, Totowa, N.J., 490 pages; Protein Purification, Principles and Practices, (1993) Scopes R. K., Springer-Verlag, N.Y., 3^(rd) Edition, 380 pages; Current Protocols in Immunology, (1999) Edited by Coligan J. E. et al., John Wiley & Sons Inc., N.Y., are herein incorporated by reference.

For recombinant production, host cells are transfected with vectors which encode the polypeptides, and then cultured in a nutrient media modified as appropriate for activating promoters, selecting transformants or amplifying the genes. Suitable vectors are those that are viable and replicable in the chosen host and include chromosomal, non-chromosomal and synthetic DNA sequences e.g. bacterial plasmids, phage DNA, baculovirus, yeast plasmids, vectors derived from combinations of plasmids and phage DNA. The polypeptide sequence may be incorporated in the vector at the appropriate site using restriction enzymes such that it is operably linked to an expression control region comprising a promoter, ribosome binding site (consensus region or Shine-Dalgarno sequence), and optionally an operator (control element). One can select individual components of the expression control region that are appropriate for a given host and vector according to established molecular biology principles (Sambrook et al., (1989) Molecular Cloning: A Laboratory manual, 2^(nd) ed., Cold Spring Harbor, N.Y.; Current Protocols in Molecular Biology, (1999) Edited by Ausubel F. M. et al., John Wikey & Sons, Inc., N.Y., incorporated herein by reference). Suitable promoters include but are not limited to LTR or SV40 promoter, E. coli lac, tac or trp promoters and the phage lambda P_(L) promoter. Vectors will preferably incorporate an origin of replication as well as selection markers, i.e. antibiotic resistance gene. Suitable bacterial vectors include pET, pQE70, pQE60, pQE-9, pD10 phagescript, PSIX174, pBluescript SK, pbsks, pNH8A, pNH16A, pNH46A, ptrc99a, pKK223-3, pKK233-3, pDR540, pRIT5 and eukaryotic vectors pBlueBacIII, pWLNEO, pSV2CAT, pOG44, pXT1, pSG, pSVK3, pBPV, pMSG and pSVL. Host cells may be bacterial (i.e. E. coli, Bacillus subtilis, Streptomyces), fungial (i.e. Aspergillus niger, Aspergillus nidulins), yeast (i.e. Saccharomyces) or eukaryotic (i.e. CHO, COS).

Upon expression of the polypeptide in culture, cells are typically harvested by centrifugation then disrupted by physical or chemical means (if the expressed polypeptide is not secreted into the media) and the resulting crude extract retained to isolate the polypeptide of interest. Purification of the polypeptide from culture media or lysate may be achieved by established techniques depending on the properties of the polypeptide.e. using ammonium sulfate or ethanol precipitation, acid extraction, anion or cation exchange chromatography, phosphocellulose chromatography hydrophobic interaction chromatography, hydroxylapatite chromatography and lectin chromatography. Final purification may be achieved using HPLC.

The polypeptide may be expressed with or without a leader or secretion sequence. In the former case, the leader may be removed using post-translational processing (see U.S. Pat. No. 4,431,739, U.S. Pat. No. 4,425,437 and U.S. Pat. No. 4,338,397 incorporated herein by reference) or be chemically removed subsequent to purifying the expressed polypeptide.

According to a further aspect, the GBS polypeptides of the invention may be used in a diagnostic test for GBS infection, in particular for GBS infection. Several diagnostic methods are possible, for example detecting GBS organism in a biological sample, the following procedure may be followed:

-   a. obtaining a biological sample from an individual; -   b. incubating an antibody or fragment thereof reactive with an GBS     polypeptide of the invention with the biological sample to form a     mixture, and -   c. detecting specifically bound antibody or bound fragment in the     mixture which indicates the presence of GBS.

Alternatively, a method for the detection of antibody specific to a GBS antigen in a biological sample containing or suspected of containing said antibody may be performed as follows:

-   a. obtaining a biological sample from an individual; -   b. incubating one or more GBS polypeptides of the invention or     fragments thereof with the biological sample to form a mixture; and -   c. detecting specifically bound antigen or bound fragment in the     mixture which indicates the presence of antibody specific to GBS.

One of skill in the art will recognize that this diagnostic test may take several forms, including an immunological test such as an enzyme-linked immunoadsorbent assay (ELISA), a radioimmunoassay or a latex agglutination assay, essentially to determine whether antibodies specific for the polypeptide are present in an organism.

The polynucleotides encoding polypeptides of the invention may also be used to design DNA probes for use in detecting the presence of GBS in a biological sample suspected of containing such bacteria. The detection method of this invention comprises:

-   a. obtaining the biological sample from an individual; -   b. incubating one or more DNA probes having a DNA sequence encoding     a polypeptide of the invention or fragments thereof with the     biological sample to form a mixture; and -   c. detecting specifically bound DNA probe in the mixture which     indicates the presence of GBS bacteria.

The DNA probes of this invention may also be used for detecting circulating GBS (i.e. GBS nucleic acids) in a sample, for example using a polymerase chain reaction, as a method of diagnosing GBS infections. The probe may be synthesized using conventional techniques and may be immobilized on a solid phase or may be labelled with a detectable label. A preferred DNA probe for this application is an oligomer having a sequence complementary to at least about 6 contiguous nucleotides of the GBS polypeptides of the invention.

Another diagnostic method for the detection of GBS in an individual comprises:

-   a. labelling an antibody reactive with a polypeptide of the     invention or fragment thereof with a detectable label; -   b. administering the labelled antibody or labelled fragment to the     individual; and -   c. detecting specifically bound labelled antibody or labelled     fragment in the individual which indicates the presence of GBS.

A further aspect of the invention is the use of the GBS polypeptides of the invention as immunogens for the production of specific antibodies for the diagnosis and in particular the treatment of GBS infection. Suitable antibodies may be determined using appropriate screening methods, for example by measuring the ability of a particular antibody to passively protect against GBS infection in a test model. One example of an animal model is the mouse model described in the example herein. The antibody may be a whole antibody or an antigen-binding fragment thereof and may belong to any immunoglobulin class. The antibody or fragment may be of animal origin, specifically of mammalian origin and more specifically of murine, rat or human origin. It may be a natural antibody or a fragment thereof, or if desired, a recombinant antibody or antibody fragment. The term recombinant antibody or antibody fragment means antibody or antibody fragment which was produced using molecular biology techniques. The antibody or antibody fragments may be polyclonal or preferably monoclonal. It may be specific for a number of epitopes associated with the GBS polypeptides but is preferably specific for one.

A further aspect of the invention is the use of a pharmaceutical composition of the invention for the prophylactic or therapeutic treatment of GBS infection comprising administering to said individual a prophylactic or therapeutic amount of the composition.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belong. All publications, patent applications, patents and other references mentioned herein are incorporated by reference in their entirety. In case of conflict, the present specification including definitions, will control. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting.

EXAMPLE 1

This example illustrates the identification of GBS BVH-A2 and BVH-A3 genes.

Chromosomal DNA was isolated from different GBS strains as previously described (Jayarao B M et al. 1991. J. Clin. Microbiol. 29:2774-2778). A λZAPExpress genomic library was constructed using chromosomal DNA purified from the serotype III GBS strain NCS954 and screened according to the manufacturer's instruction (Stratagene, La Jolla, Calif.) with a pool of human normal sera. Briefly, the purified chromosomal DNA was partially digested with tsp509I restriction enzyme, and the resulting fragments were electrophoresed on a 1% agarose gel (Bio-Rad). Fragments in the 5- to 10-kb size range were extracted from the gel and ligated to the EcoRI arms of λZAPExpress vector and the vector was encapsidated using the Gigapack II packaging extract (Stratagene). The recombinant phages were used to infect E. coli XL1-Blue MRF′[Δ(mcrA)183Δ(mcrCB-hsdSMR-mrr)173 endA1 supE44 thi-1 recA1 gyrA96 relA1 lac (F′ proAB lacl^(q)ZΔM15 Tn10 [Tet^(R)])], which was then plated onto LB agar. The resulting plaques were lifted onto Hybond-C nitrocellulose membranes (Amersham Pharmacia Biotech, Baie d'Urfée, Canada) pre-impregnated with 10 mM Isopropyl-β-d-thiogalactopyranoside (IPTG: ICN Biomedicals Inc., Costa Mesa, Calif.). The membranes were blocked using phosphate-buffered saline (PBS) with 3% skim milk and were sequentially incubated with the pooled of human sera, peroxydase-labeled goat anti-human immunoglobulins antisera (Jackson Immunoresearch Laboratories Inc., West Grove, Pa.) and substrate. Positive plaques were isolated, purified twice, and the recombinant pBK-CMV plasmids (Stratagene) were excised with the ExAssist helper phage (Stratagene) according to the manufacturer's instructions. Immunoblots using phagemid vectors containing the cloned inserts revealed that the pooled human sera reacted with a protein band with an approximate molecular weight of 65 kDa for the clone H31-29, while it reacted with two protein bands with an approximate molecular weights between 40-60 kDa for the clone F8. These clones were respectively identified as BVH-A2 and BVH-A3. The sequence of the inserts were determined using the TAQ Dye Deoxy Terminator Cycle Sequencing Kit with an Applied Biosystems Inc. (Foster City, Calif.) automated sequencer model 373A according to the manufacturer's recommendations.

EXAMPLE 2

This example illustrates the cloning of GBS BVH-A2 and BVH-A3 genes.

The coding regions of Group B streptococcal BVH-A2 (SEQ ID NO: 1) and BVH-A3 (SEQ ID NO: 5) genes were respectively amplified by PCR (DNA Thermal Cycler GeneAmp PCR system 2400 Perkin Elmer, San Jose, Calif.) from purified recombinant phagemid clone H31-29 and genomic DNA of serotype III Group^(1′) B streptococcal strain NCS954 using oligonucleotide primers that contained base extensions for the addition of restriction sites NdeI (CATATG) and XhoI (CTCGAG). The oligonucleotide primers (Table 1) DMAR172 (SEQ ID No:9) and DMAR173 (SEQ ID No:10) were used to amplify the BVH-A2 gene, while DMAR204 (SEQ ID No:15) and DMAR205 (SEQ ID No:16) were used to amplify the BVH-A3 gene. PCR products were purified from agarose gel using a QIAquick gel extraction kit from QIAgen following the manufacturer's instructions (Chatsworth, Calif.), and digested with NdeI and XhoI (Pharmacia Canada Inc, Baie d'Urfé, Canada). The pET-21b(+) vector (Novagen, Madison, Wis.) was digested with NdeI and XhoI and purified from agarose gel using a QIAquick gel extraction kit from QIAgen (Chatsworth, Calif.). The NdeI-XhoI PCR products were ligated to the NdeI-XhoI pET-21b(+)expression vector. The ligated products were transformed into E. coli strain DH5α [φ80dlacZΔM15 Δ(lacZYA-argF)U169 endA1 recA1 hsdR17(r_(K)−m_(K)+) deoR thi-1 supE44 λ⁻gyrA96 relA1] (Gibco BRL, Gaithersburg, Md.) according to the method of Simanis (Hanahan, D. DNA Cloning, 1985, D. M. Glover (ed), pp. 109-135). Recombinant pET-21b(+)plasmids (rpET21b(+)) containing BVH-A2 or BVH-A3 genes were purified using a QIAgen plasmid kit (Chatsworth, Calif.) and DNA inserts were sequenced (Taq Dye Deoxy Terminator Cycle Sequencing kit, ABI, Foster City, Calif.).

It was determined that the open reading frame (ORF) which codes for BVH-A2 gene (SEQ ID NO: 1) contains 1626-bp and encodes a 541 amino acid residues polypeptide with a predicted pI of 8.99 and a predicted molecular mass of 59730.66 Da. Analysis of the predicted amino acid residues sequence (SEQ ID NO:3)using the Spscan software (Wisconsin Sequence Analysis Package; Genetics Computer Group) suggested the existence of a 37 amino acid residues signal peptide (MRGSLSTKQSYSLRKYKFGLASVILGSFIMVTSPVFA), which end with a cleavage site situated between an alanine and a aspartic acid residues. Analysis of this ORP did not revealed the presence of repetitive structures, or IgA binding motif (MLKKIE), but a putative cell wall anchoring motif (LPKTG) was identified near the C-terminal end between amino acid residues 479 and 483. Comparison of the amino acid sequence of BVH-A2 (SEQ ID NO.3)with the sequences compiled in the available databanks revealed 18% identity with an hypothetical 40 kDa transmembrane exported protein of Streptococcus mutans which was located upstream the sr gene encoding the SR protein implicated in the interactions of S. mutans with salivary glycoproteins (GeneBank accession number: c60328: Ogier et al 1991. Infection and Immunity.59:1620-1626).

TABLE 1 Oligonucleotide primers used for PCR amplifications of GBS BVH-A2 and BVH-A3 genes Oligonucleotide Genes primers I.D. Sequences BVH-A2 DMAR172 5′-CTTTGGGGAACATATGAGGGGATCTC-3′ (SEQ ID No 9) BVH-A2 DMAR173 5′-CTAAAAAGATTTACTCGAGAATTTCAATATAGCG-3′ (SEQ ID No 10) BVH-A2 DMAR373 5′-ATGAGGGGATCTCTCAGTACTAAGCAATCTT-3′ (SEQ ID No 11) BVH-A2 DMAR374 5′-TTAAATTTCAATATAGCGACGAATACCGGA-3′ (SEQ ID No 12) BVH-A2 DMAR464 5′-CATAGGATCCGGATCAAACTACATCGGTTCAAG-3′ (SEQ ID No 13) BVH-A2 DMAR465 5′-CCGGGTCGACTTAAATTTCAATATAGCGACG-3′ (SEQ ID No 14) BVH-A3 DMAR204 5′-CACAGGAGAACATATGAAGATTAAAAAAATTATTAGT (SEQ ID No 15) GGCTTTGCC-3′ BVH-A3 DMAR205 5′-CTTTCTCGAGTGCACCTTGATGGCGATCAGC-3′ (SEQ ID No 16) BVH-A3 DMAR466 5′-CATAGGATCCTGATGACACCACCAGTGAGTATCACTA (SEQ ID No 17) TATC-3′ BVH-A3 DMAR467 5′-CATAGTCGACTTATGCACCTTGATGGCGATCAG-3′ (SEQ ID No 18)

It was determined that the open reading frame (ORF) which codes for BVH-A3 gene (SEQ ID NO:5) contains 1590-bp and encodes a 529 amino acid residues polypeptide with a predicted pI of 6.14 and a predicted molecular mass of 59019.48 Da. Analysis of the predicted amino acid residues sequence (SEQ ID NO:7) using the Spscan software (Wisconsin Sequence Analysis Package; Genetics Computer Group) suggested the existence of a 28 amino acid residues signal peptide (MKIKKIISGFAAALIISSLSTINYEVKA), which ends with a cleavage site situated between an alanine and an aspartic acid residues. Analysis of this ORF did not revealed the presence of repetitive structures, cell wall anchoring motif (LPXTG), or IgA binding motif (MLKKIE). Comparison of the amino acid sequence of BVH-A3 (SEQ ID NO.7) with the sequences compiled in the available databanks did not reveal any significant homology with sequences available in the databanks.

EXAMPLE 3

This example describes the PCR amplification of GBS BVH-A2 and BVH-A3 genes from other GBS strains

To confirm the presence by PCR amplification of BVH-A2 (SEQ ID NO:1) and BVH-A3 (SEQ ID NO:5) genes, the following 11 serologically distinct GBS strains were used: C388/90 (serotype Ia/c), ATCC12401 (serotype Ib), ATCC27591 (serotype Ic), NCS246 (serotype II/R), NCS954 (serotype III), NCS97SR331 (serotype IV), NCS535 (serotype V), NCS9842 (serotype VI), NCS7271 (serotype VII), NCS970886 (serotype VIII), ATCC27956 (bovine isolate). These strains were obtained from the American Type Culture Collection (Rockville, Md., USA) and National Centre for Streptococcus, Provincial Laboratory of Public Health for Northern Alberta (Edmonton, Canada). The E. coli strain XL1-Blue MRF′ was used in these experiments as negative control. Chromosomal DNA was isolated from each Group B streptococcal strain as previously described (Jayarao BM et al. 1991. J. Clin. Microbiol. 29:2774-2778). BVH-A2 (SEQ ID NO:1) and BVH-A3 (SEQ ID NO:5) genes were amplified by PCR(DNA Thermal Cycler GeneAmp PCR system 2400 Perkin Elmer, San Jose, Calif.) from the genomic DNA purified from the 11 GBS strains, and the control E. coli strain using the oligonucleotides presented in Table 1. The oligonucleotide primers DMAR373 (SEQ ID No:11) and DMAR374 (SEQ ID No:12) were used to amplify the BVH-A2 (SEQ ID NO:1) gene, while DMAR204 (SEQ ID No:15) and DMAR205 (SEQ ID No:16) were used to amplify the BVH-A3 (SEQ ID NO:5) gene. PCR was performed with 35 cycles of 45 sec at 94° C., 45 sec at 55° C. and 2 min at 72° C. and a final elongation period of 10 min at 72° C. The PCR products were size fractionated in 1% agarose gels and were visualized by ethidium bromide staining. The results of these PCR amplifications are presented in Table 2. The analysis of the amplification products revealed that both BVH-A2 (SEQ ID NO:1) and BVH-A3 (SEQ ID NO:5) genes were present in the genome of all of the 11 GBS strains tested. No such product was detected when the control E. coli DNA was submitted to identical PCR amplifications with both sets of oligonucleotide primers.

TABLE 2 Identification of BVH-A2 and BVH-A3 genes by PCR amplification Identification by PCR Strains identification amplification of GBS isolates BVH-A2 BVH-A3 C388/90 (serotype Ia/c) + + ATCC12401 (serotype Ib) + + ATCC27591 (serotype Ic) + + NCS246 (serotype II/R) + + NCS954 (serotype III) + + NCS97SR331 (serotype IV) + + NCS535 (serotype V) + + NCS9842 (serotype VI) + + NCS7271 (serotype VII) + + NCS970886 (serotype VIII) + + ATCC27956 (bovine isolate) + + E. coli − − control strain XL1 Blue MRF′

EXAMPLE 4

This example illustrates the cloning of GBS BVH-A2 and BVH-A3 genes in CMV plasmid PCMV-GH.

The DNA coding region of Group B streptococcal BHV-A2 (SEQ ID NO:4) and BVH-A3 (SEQ ID NO:8) polypeptides were inserted in phase downstream of a human growth hormone (hGH) gene which was under the transcriptional control of the cytomegalovirus (CMV) promotor in the plasmid vector pCMV-GH (Tang et al., Nature, 1992, 356:152). The CMV promotor is non functional plasmid in E. coli cells but active upon administration of the plasmid in eukaryotic cells. The vector also incorporated the ampicillin resistance gene.

The coding regions of BVH-A2 (SEQ ID NO: 2) and BVH-A3 (SEQ ID NO: 6) genes without their leader peptide regions were amplified by PCR (DNA Thermal Cycler GeneAmp PCR system 2400 Perkin Elmer, San Jose, Calif.) from genomic DNA of serotype III GBS strain NCS954 using oligonucleotide primers that contained base extensions for the addition of restriction sites BamHI (GGATCC) and SalI (GTCGAC). The oligonucletide primers DMAR464 (SEQ ID No:13) and DMAR465 (SEQ ID No:14) were used to amplify the BVH-A2 (SEQ ID NO:2) gene, while DMAR466 (SEQ ID No:17) and DMAR467 (SEQ ID No:18) were used to amplify the BVH-A3 (SEQ ID NO:6) genes. The PCR products were purified from agarose gel using a QIAquick gel extraction kit from QIAgen (Chatsworth, Calif.), digested with restriction enzymes (Pharmacia Canada Inc, Baie d'Urfe, Canada). The pCMV-GH vector (Laboratory of Dr. Stephen A. Johnston, Department of Biochemistry, The University of Texas, Dallas, Tex.) was digested with BamHI and SalI and purified from agarose gel using the QIAquick gel extraction kit from QIAgen (Chatsworth, Calif.). The BamHI-SalI DNA fragments were ligated to the BamHI-SalI pCMV-GH vector to create the hGH-BVH-A2 and hGH-BVH-A3 fusion polypeptides under the control of the CMV promoter. The ligated products were transformed into E. coli strain DH5α [φ80dlacZΔM15 Δ(lacZYA-argF)U169 endA1 recA1 hsdR17(r_(K)−m_(K)+) deoR thi-1 supE44 λ⁻gyrA96 relA1] (Gibco BRL, Gaithersburg, Md.) according to the method of Simanis (Hanahan, D. DNA Cloning, 1985, D. M. Glover (ed), pp. 109-135). The recombinant pCMV plasmids were purified using a QIAgen plasmid kit (Chatsworth, Calif.) and the nucleotide sequences of the DNA inserts were verified by DNA sequencing.

EXAMPLE 5

This example illustrates the use of DNA to elicit an immune response to GBS BVH-A2 and BVH-A3 polypeptide antigens.

Groups of 8 female BALB/c mice (Charles River, St-Constant, Québec, Canada) are immunized by intramuscular injection of 100 μl three times at two- or three-week intervals with 50 μg of recombinant pCMV-GH encoding BVH-A2 (SEQ ID NO:2) or BVH-A3 (SEQ ID NO:6) genes in presence of 50 μg of granulocyte-macrophage colony-stimulating factor (GM-CSF)-expressing plasmid pCMV-GH-GM-CSF (Laboratory of Dr. Stephen A. Johnston, Department of Biochemistry, The University of Texas, Dallas, Tex.). As control, groups of mice are injected with 50 μg of pCMV-GH in presence of 50 μg of pCMV-GH-GM-CSF. Blood samples are collected from the orbital sinus prior to each immunization and seven days following the third injection and serum antibody responses are determined by ELISA using either purified BVH-A2-His.Tag or BVH-A3-His.Tag recombinant polypeptides as coating antigens.

EXAMPLE 6

This example illustrates the production and purification of recombinant GBS BVH-A2 and BVH-A3 polypeptides.

The recombinant pET-21b(+)plasmids with BVH-A2 or BVH-A3 genes respectively corresponding to the SEQ ID NO: 1, and SEQ ID NO: 5 are used to transform by electroporation (Gene Pulser II apparatus, BIO-RAD Labs, Mississauga, Canada) E. coli strain BL21(DE3) (F⁻ompT hsdS_(B) (r⁻ _(B)m⁻ _(B)) gal dcm (DE3)) (Novagen, Madison, Wis.). In this strain of E. coli, the T7 promotor controlling expression of the recombinant polypeptide is specifically recognized by the T7 RNA polymerase (present on the λDE3 prophage) whose gene is under the control of the lac promotor which is inducible by isopropyl-β-d-thio-galactopyranoside (IPTG). The transformants BL21(DE3)/rpET are grown at 37° C. with agitation at 250 rpm in LB broth (peptone 10 g/L, yeast extract 5 g/L, NaCl 10 g/L) containing 100 μg of carbenicillin (Sigma-Aldrich Canada Ltd., Oakville, Canada) per mL until the A₆₀₀ reaches a value of 0.6. In order to induce the production of GBS BVH-A2-His.Tag and BVH-A3-His.Tag recombinant polypeptides, the cells are incubated for 3 additional hours in the presence of IPTG at a final concentration of 1 mM. Induced cells from a 500 ml culture are pelleted by centrifugation and frozen at −70° C.

The purification of the recombinant polypeptides from the soluble cytoplasmic fraction of IPTG-induced BL21(DE3)/rpET21b(+) is done by affinity chromatography based on the properties of the His.Tag sequence (6 consecutive histidine residues) to bind to divalent cations (Ni²⁺) immobilized on the His.Bind metal chelation resin. Briefly, the pelleted cells obtained from a 500 mL culture induced with IPTG are resuspended in lysis buffer (20 mM Tris, 500 mM NaCl, 10 mM imidazole, pH 7.9) containing 1 mM PMSF, sonicated and centrifuged at 12,000×g for 20 min to remove debris. The supernatant is deposited on a Ni-NTA agarose column (Qiagen, Mississauga, Ontario, Canada). The GBS BVH-A2-His.Tag and BVH-A3-His.Tag recombinant polypeptides are eluted with 250 mM imidazole-500 mM NaCl-20 mM Tris pH 7.9. The removal of the salt and imidazole from the samples is done by dialysis against PBS at 40° C. The quantities of recombinant polypeptides obtained from the soluble fraction of E. coli are estimated by MicroBCA (Pierce, Rockford, Ill.).

EXAMPLE 7

This example illustrates the accessibility to antibodies of the GBS BVH-A2 and BVH-A3 polypeptides at the surface of GBS strains.

Bacteria are grown in Todd Hewitt (TH) broth (Difco Laboratories, Detroit Mich.) with 0.5% Yeast extract (Difco Laboratories) and 0.5% peptone extract (Merck, Darmstadt, Germany) at 37° C. in a 8% CO₂ atmosphere to give an OD₄₉₀ nm of 0.600 (˜10⁸ CFU/ml). Dilutions of anti-BVH-A2, anti-BVH-A3 or control sera are then added and allowed to bind to the cells, which are incubated for 2 h at 4° C. Samples are washed 4 times in blocking buffer [phosphate-buffered saline (PBS) containing 2% bovine serum albumin (BSA)], and then 1 mL of goat fluorescein (FITC)-conjugated anti-mouse IgG+IgM diluted in blocking buffer is added. After an additional incubation of 60 min at room temperature, samples are washed 4 times in blocking buffer and fixed with 0.25% formaldehyde in PBS buffer for 18-24 h at 4° C. Cells are washed 2 times in PBS buffer and resuspended in 500 μl of PBS buffer. Cells are kept in the dark at 4° C. until analyzed by flow cytometry (Epics® XL; Beckman Coulter, Inc.).

EXAMPLE 8

This example illustrates the protection against fatal GBS infection induced by passive immunization of mice with rabbit hyper-immune sera.

New Zealand rabbits (Charles River laboratories, St-Constant, Canada) are injected subcutaneously at multiple sites with 50 μg and 100 μg of BVH-A2-His.Tag or BVH-A3-His.Tag polypeptides that are produced and purified as described in Example 6 and adsorbed to Alhydrogel adjuvant (Superfos Biosector a/s). Rabbits are immunized three times at three-week intervals with the BVH-A2-His.Tag or BVH-A3-His.Tag polypeptides. Blood samples are collected three weeks after the third injection. The antibodies present in the serum are purified by precipitation using 40% saturated ammonium sulfate. Groups of 10 female CD-1 mice (Charles River) are injected intravenously with 500 μl of purified serum collected either from BVH-A2-His.Tag, or BVH-A3-His.Tag immunized rabbits, or rabbits immunized with an unrelated control recombinant protein. Eighteen hours later the mice are challenged with approximately 8×10⁴ CFU of the GBS strain C388/90 (Ia/c). Samples of the GBS challenge inoculum are plated on blood agar plates to determine the CFU and to verify the challenge dose. Deaths are recorded for a period of 14 days.

EXAMPLE 9

This example illustrates the protection of mice against fatal GBS infection induced by immunization.

Groups of 8 female CD-1 mice (Charles River) are immunized subcutaneously three times at three-week intervals with 20 μg of either BVH-A2-His.Tag or BVH-A3-His.Tag polypeptides that are produced and purified as described in Example 6 in presence of 10 μg of QuilA adjuvant (Cedarlane Laboratories Ltd, Hornby, Canada). The control mice are injected with QuilA adjuvant alone in PBS. Blood samples are collected from the orbital sinus on day 1, 22 and 43 prior to each immunization and seven days (day 50) following the third injection. Two weeks later the mice are challenged with approximately 8×10⁴ CPU of the GBS strain C388/90 (Ia/c). Samples of the GBS challenge inoculum are plated on blood agar plates to determine the CFU and to verify the challenge dose. Deaths are recorded for a period of 14 days. 

1. An isolated polypeptide comprising an amino acid sequence at least 95% identical to the amino acid sequence set forth in either SEQ ID NO:7 or SEQ ID NO:8, wherein the isolated polypeptide is capable of raising antibodies that specifically bind to a polypeptide comprising the amino acid sequence set forth in either SEQ ID NO:7 or SEQ ID NO:8.
 2. An isolated polypeptide comprising: (a) the amino acid sequence set forth in SEQ ID NO:7; (b) the amino acid sequence set forth in SEQ ID NO: 8; (c) the polypeptide of (a), wherein the N-terminal methionine residue is deleted; or (d) the polypeptide of (a), wherein the signal peptide amino acid sequence is deleted.
 3. A chimeric polypeptide comprising two or more polypeptides wherein each of the two or more polypeptides comprises at least twenty contiguous amino acids of the amino acid set forth in SEQ ID NO:8, and wherein the two or more polypeptides are linked as to form a chimeric polypeptide.
 4. A chimeric polypeptide comprising two or more polypeptides wherein each of the two or more polypeptides comprises a sequence chosen from SEQ ID NOS: 7 and 8, and wherein the two or more polypeptides are linked as to form a chimeric polypeptide.
 5. A pharmaceutical composition comprising a polypeptide according to claim 1 or claim 2 and a pharmaceutically acceptable carrier, diluent or adjuvant.
 6. A kit comprising the polypeptide according to either claim 1 or claim 2 for detection or diagnosis of a group B Streptococcus infection.
 7. An isolated polypeptide comprising a fragment that comprises at least twenty contiguous amino acids of the amino acid sequence set forth in SEQ ID NO:8, wherein the isolated polypeptide is capable of raising antibodies that specifically bind to a polypeptide comprising the amino acid sequence set forth in either SEQ ID NO:7 or SEQ ID NO:8.
 8. A pharmaceutical composition comprising the polypeptide according to claim 7 and a pharmaceutically acceptable carrier, diluent, or adjuvant. 